Misconceptions about Immunization

Misconception #9:Vaccines cause autism

On October 3, 1999, Cable News Network aired a program
on which the parents of three-year-old Liam Reynolds stated that
he had developed autism two weeks after receiving measles, mumps
and rubella (MMR) vaccine [1]. The program included the views
of Stephanie Cave, M.D., a Louisiana physician who "specializes
in treating autism" with diet and nutritional supplements
[2]. An American Academy of Pediatrics official and explained
why there was no reason to believe that a link exists between autism
and vaccination. But the dramatic before-and-after videotapes
of the child probably had enough impact to persuade many parents
to avoid having their children vaccinated. The program's narrator
stated there had been "a puzzling jump in the number of children
being diagnosed with autism." However, the number being diagnosed
may reflect increased reporting of cases rather than an increase
in actual incidence.

Autism is a chronic developmental disorder characterized by
problems in social interaction, communication, and restrictive
and repetitive interests and activities. Autism may be initially
noted in infancy as impaired attachment, but it is most often
first identified in toddlers, mostly boys, from 18 to 30 months
of age. Boys are 3-4 times more likely to be afflicted with autism
than girls. Girls as a group, however, may be more severely affected.
Correct diagnosis of autism depends on an accurate developmental
history focused on types of behaviors typical of autism and on
evaluation of functional skills. Approximately 75% of persons
with autism are mentally retarded. Fewer than 5% of children with
autistic traits have fragile X or another known chromosomal abnormality.
Although no cure exists, autism is treatable. Symptoms associated
with autism often improve as children start to acquire language
and learn how to communicate their needs.

In most cases of autism, no cause is apparent. In a few cases,
biologic causes have been identified, although none are unique
to autism. Some prenatal factors include intrauterine rubella;
tuberous sclerosis; chromosomal abnormalities, such as Down's
syndrome; as well as brain abnormalities, such as hydrocephalus.
Frequently cited postnatal conditions associated with autism are
untreated phenylketonuria, infantile spasms, and herpes simplex
encephalitis. In the majority of cases, however, no underlying
cause can be identified.

The current theory favored by many experts is that autism is
a genetically-based disorder that occurs before birth [3]. Studies
of persons with autism are finding abnormalities in brain structures
that develop in the first few weeks of fetal development [4].
Evidence that genetics is an important, but not exclusive, cause
of autism includes a 3-8% risk of recurrence in families with
one affected child. A working group convened by the National Institutes
of Health in 1995 reached a consensus that autism is a genetic
condition. An issue unresolved by the group was the role of immune
factors in autism spectrum disorders; it was suggested that studies
to clarify the situation are needed.

No Evidence of Link

Some parents of children with autism believe that there is
a link between measles, mumps, rubella (MMR) vaccine and autism.
However, there is no sensible reason to believe that any vaccine
can cause autism or any kind of behavioral disorder. Typically,
symptoms of autism are first noted by parents as their child begins
to have difficulty with delays in speaking after age one. MMR
vaccine is first given to children at 12-15 months of age. Since
this is also an age when autism commonly becomes apparent, it
is not surprising that autism follows MMR immunization in some
cases. However, by far the most logical explanation is coincidence, not cause-and-effect.

If measles vaccine or any other vaccine causes autism, it would
have to be a very rare occurrence, because millions of children
have received vaccines without ill health effects. The only "evidence"
linking MMR vaccine and autism was published in the British journal Lancet in 1998 [5]. An editorial published in the same
issue, however, discussed concerns about the validity of the study
[6]. Based on data from 12 patients, Dr. Andrew Wakefield (a British
gastroenterologist) and colleagues speculated that MMR vaccine
may have been the possible cause of bowel problems which led to
a decreased absorption of essential vitamins and nutrients which
resulted in developmental disorders like autism. No scientific
analyses were reported, however, to substantiate the theory. Whether
this series of 12 cases represent an unusual or unique clinical
syndrome is difficult to judge without knowing the size of the
patient population and time period over which the cases were identified.
If there happened to be selective referral of patients with autism
to the researchers' practice, for example, the reported case series
may simply reflect such referral bias. Moreover, the theory that
autism may be caused by poor absorption of nutrients due to bowel
inflammation is senseless and is not supported by the clinical
data. In at least 4 of the 12 cases, behavioral problems appeared
before the onset of symptoms of inflammatory bowel disease. Furthermore,
since publication of their original report in February of 1998,
Wakefield and colleagues have published another study in which
highly specific laboratory assays in patients with inflammatory
bowel disease, the posited mechanism for autism after MMR vaccination,
were negative for measles virus [7,8].

Other recent investigations also do not support a causal association
between MMR (or other measles-containing vaccines) and autism
or inflammatory bowel disease (IBD) [9-13]. In one investigation,
a Working Party on MMR Vaccine of the United Kingdom's Committee
on Safety of Medicines (1999) was charged with the evaluation
of several hundred reports, collected by a firm of lawyers, of
autism, Crohn's disease, or similar disorders developing after
receipt of MMR or MR vaccines. The Working Party conducted a systematic,
standardized review of parental and physician information. Although
acknowledging that it is impossible to prove or refute the suggested
associations (because of variable data quality, biased selection
of cases, and lack of a control group), the Working Party concluded
that the information available "... did not support the suggested
causal associations or give cause for concern about the safety
of MMR or MR vaccines." [12] In March 2000, a Medical Research
Council report concludes that between March 1998 and September
1999 no new evidence had suggested a causal link between MMR and
autism or IBD [13]. The American Medical Association has reached
the same conclusion.

A study by Taylor and colleagues provides population-based
evidence that overcomes many of the limitations faced by the Working
Party and by Wakefield and colleagues [14,15]. The authors identified
all 498 known cases of autism spectrum disorders (ASD) in certain
districts of London born in 1979 or later and linked them to an
independent regional vaccination registry. ASD includes classical
autism, atypical autism, and Asperger's
syndrome, but the results were similar when cases of classical
autism were analyzed separately. The authors noted:

The known number of ASD cases has been increasing since 1979,
but there was no jump after the introduction of MMR vaccine in
1988.

Cases vaccinated before 18 months of age had similar ages
at diagnosis as did cases who had been vaccinated after 18 months
or not vaccinated, indicating that vaccination does not result
in earlier expression of autistic characteristics.

At age two years, the MMR vaccination coverage among the
ASD cases was nearly identical to coverage in children in the
same birth cohorts in the whole region, providing evidence of
an overall lack of association with vaccination.

The first diagnosis of autism or initial signs of behavioral
regression were not more likely to occur within time periods
following vaccination than during other time periods.

A weak statistical association existed between MMR vaccination
and initial parental concern, but this appears to have been due
to parents' difficulty in recalling precise age at onset and
a preference for approximating the age as 18 months.

A study of the population of children in two communities in
Sweden also found no evidence of an association between MMR vaccination
and autism [16]. That study found no difference in the prevalence
of autism in children born after the introduction of MMR vaccination
in Sweden compared with children born before.

In January 1990, an Institute of Medicine committee examining
possible health effects associated with DPT vaccine concluded
that there was no evidence to indicate a causal relation between
DPT vaccine or the pertussis component of DPT vaccine and autism
[17]. Also, data obtained from CDC's Monitoring System for Adverse
Events Following Immunization (MASAEFI) system, showed no reports
of autism occurring within 28 days of DPT immunization from 1978-1990,
a period in which approximately 80.1 million doses of DPT vaccine
were administered in the United States. From January 1990 through
February 1998, only 15 cases of autism behavior disorder after
immunization were reported to the Vaccine Adverse Events Reporting
System (VAERS). Because of the small number of reports over an
8-year period, the cases reported are likely to represent unrelated
chance occurrences that happened around the time of vaccination.
The most frequent vaccines cited in the reports were diphtheria,
tetanus, pertussis (DPT), oral polio vaccine (OPV), and MMR. Other
vaccines reported as having a possible association with autism
were Haemophilus influenzae type B and Hepatitis B.

In 2000, the American Academy of Pediatrics convened a multidisciplinary
panel of experts ro review what is known about the development,
epidemiology, and genetics of ASD and the hypothesized associations
with IBD, measles, and MMR vaccine. The panel concluded:

Although the possible association with MMR vaccine has received
much public and political attention and there are many who have
derived their own conclusions based on personal experiences,
the available evidence does not support the hypothesis that MMR
vaccine causes autism or associated disorders or IBD. Separate
administration of measles, mumps, and rubella vaccines to children
provides no benefit over administration of the combination MMR
vaccine and would result in delayed or missed immunizations.
Pediatricians need to work with families to ensure that children
are protected early in the second year of life from these preventable
diseases. Continued scientific efforts need to be directed to
the identification of the causes of ASD [18].

The fact that autism is diagnosed during the second or third
year of life does not mean that it began at that age. Analyses
of home movies made from birth onward have shown that most children
who are diagnosed as autistic during the second or third year
have abnormal signs during the first year—and some even show
abnormalities at birth [19-26].

Recently, the National Childhood Encephalopathy Study (NCES)
was examined to see if there was any link between measles vaccine
and neurological events. Researchers in England found no indication
that measles vaccine contributes to the development of educational
and behavioral deficits or other possible signs of long-term neurological
damage [27].

Most people have no adverse reaction after receiving a MMR
vaccination. About 5%-15% of vaccines may develop a fever 5-12
days after MMR vaccination and 5% may develop a rash. Central
nervous system conditions, including encephalitis and encephalopathy,
have been reported with a frequency of less than one per million
doses administered. In July 2002, after Wakefield testified before
a U.S. Congressional committee chaired by a vaccine opponent,
Dr. Michael Fitzpatrick (a British general physician and parenbt
of an autistic child) charged that Wakefield "has opted out
of medical science to join the world of pseudoscientific dogma,
media celebrity and populist campaigning." [29] In a devastating
review of the conduct of Wakefield and Paul Shattock, a pharmacist
and vaccine opponent who runs the so-called Autism
Research Unit at the University of Sunderland, Fitzpatrick
stated:

There is now a flourishing network of private laboratories
offering urine and blood tests of the sort carried out by Mr
Shattock—all of no recognised diagnostic value. There is a
substantial business sector selling dietary supplements, vitamins,
minerals, enzymes and all manner of special dietary products
—all of no proven therapeutic value. The common feature of
both tests and supplements is their exorbitant cost, suggesting
that high profits are being made from peddling interventions
of no proven value, often to desperate parents, many on low incomes.

There are other beneficiaries of the anti-MMR campaign. Private
GPs are now making profits of several hundred percent from selling
separate vaccines. Lawyers are eagerly collecting legal aid fees
by inflating the hopes of parents that they may gain substantial
compensation for the alleged damages from MMR through the pursuit
of litigation. It is not surprising that both are enthusiastic
supporters of Dr Wakefield's crusade. It seems that Britain's
investigative journalists are so smitten by Dr Wakefield's charisma
and so credulous towards junk science, that they are reluctant
to investigate the real abuses generated around the anti-MMR
campaign [29].

As with the administration of any agent that can produce fever,
some children may have a febrile seizure. Most that follow measles
vaccination are simple febrile seizures and affect children without
known risk factors. An increased risk of febrile convulsions may
occur among children with a prior history of convulsions.

The Bottom Line

There are no proven data to suggest that measles vaccine will
increase the risk of developing autism or any other behavioral
disorder [28]. The known benefits vastly exceed any unknown risks.
The CDC continues to recommend two doses of MMR vaccine for all
children who do not have a known medical contraindication; the
first dose is recommended at 12-15 months of age and the second
dose is recommended at either 4-6 years of age or at 11-12 years
of age [30,31].

To assure the safety of vaccines, the CDC, the FDA, the National
Institutes of Health (NIH), and other federal agencies routinely
examine any new evidence that would suggest possible problems
with the safety of vaccines. Currently, CDC is conducting a study
in the metropolitan Atlanta area to further evaluate any possible
association between MMR vaccination and autism.

Immunization against measles has led to a dramatic decrease
in the incidence of measles, which is sometimes fatal. I believe
that the manner in which CNN covered this issue was extremely
irresponsible and will result in the death of children whose parents
are scared out of having their children receive it.

For Additional Information.

Liam's mother Shelley H. Reynolds founded and serves as president
of Unlocking Autism, an organization intended to "bring the issues of autism
from individual homes to the forefront of national dialogue."
Dr. Cave is a board member described on the Web site as "a
leader and a fighter for the alternative therapies that seem
to work with many of our children. She believes in using drugs
as a last resort, concentrating instead on ascertaining the unique
biochemistry of each individual child and working to achieve
a balance through nutritional supplements and dietary interventions."
The idea that autism represents a nutritional imbalance is preposterous.